On Mon, May 07, 2007 at 04:32:56PM +0530, Srivatsa Vaddagiri wrote:> On Mon, May 07, 2007 at 04:17:24PM +0530, Gautham R Shenoy wrote:> > Nevertheless, with the freezer based approach that we're experimenting,> > this problem shouldn't arise. We expect the whole system to get frozen> > before we actually do a cpu_down() (which will then call> > __stop_machine_run). So any such rogue RT task will have to first fail> > the freezer ( which it will), > > >From what I understand of the freezer, if the RT task is running in user> space (which seems to be the case in this thread), it should get frozen even > if it is a forever running SCHED_FIFO task at MAX_RT_PRIO -1 priority?

Yes, you are right. It will end up getting the fake signal. So yeah, freezer pretty much solves the problem for cpu hotplug.

But I now wonder if we will have some problem with module stopping if we have a high prio SCHED_FIFO in the system.

> > -- > Regards,> vatsa

Regardsgautham.-- Gautham R ShenoyLinux Technology CenterIBM India."Freedom comes with a price tag of responsibility, which is still a bargain,because Freedom is priceless!"-To unsubscribe from this list: send the line "unsubscribe linux-kernel" inthe body of a message to majordomo@vger.kernel.orgMore majordomo info at http://vger.kernel.org/majordomo-info.htmlPlease read the FAQ at http://www.tux.org/lkml/